Apparatus provided with heat-exchanging means

ABSTRACT

The invention relates to an apparatus provided with heat-exchanging means comprising a housing, in which housing a tube bank is accommodated, having at both sides connecting means for the inlet and outlet of a primary medium stream and a secondary medium stream, wherein the housing comprises a wall that extends in the longitudinal direction of the tube bank wherein the wall is embodied with tubes incorporated therein or mounted thereon, through which a portion of the medium supplied to the tube bank flows.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of PatentCooperation Treaty (PCT) Patent Application Serial No.PCT/NL2005/000065, entitled “APPARATUS PROVIDED WITH HEAT-EXCHANGINGMEANS”, filed on Jan. 28, 2005, and the specification and claims thereofare incorporated herein by reference.

This application claims priority to and the benefit of the filing of TheNetherlands Patent Application Serial No. 1025538 entitled “APPARATUSPROVIDED WITH HEAT-EXCHANGING MEANS”, filed on Feb. 20, 2004, and thespecification and claims thereof are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates to an apparatus provided with heat-exchangingmeans comprising a housing, in which housing a tube bank isaccommodated, having at both sides connecting means for the inlet andoutlet of a primary medium stream and a secondary medium stream, whereinthe housing comprises a wall that extends in the longitudinal directionof the tube bank.

Such an apparatus is known in practice and is used in numeroussituations in which the transfer of heat between a primary medium streamand a secondary medium stream is to be realized.

Such an apparatus concerns, for example, a chemical reactor in which anexothermic or endothermic reaction is carried out.

The energy required for an endothermic reaction may, for example, besupplied with the primary medium stream, whilst the reaction itselftakes place in the secondary medium stream. Of course, the function ofthe primary and the secondary medium stream may also be interchanged.

Exothermic reactions also may advantageously take place in such anapparatus since the reaction heat can then be absorbed directly by aheat-removing medium stream. Some catalysts are less effective or evenbecome unstable at increasing temperatures, and then it is very usefulto be able to directly remove the reaction heat that has developed withan exothermic reaction.

Such an apparatus embodied as heat exchanger is known from NL-A-298 579.

Both the primary medium stream and the secondary medium stream may be aliquid stream, a gas stream or a mixture thereof.

A problem of the known apparatus is that in practice, the temperaturedifference between the housing whose temperature is wholly determined bythe secondary stream and the tube bank whose temperature is determinedby both streams must not be greater than approximately 50° C. Theexpansion differences resulting from greater temperature differencesincrease the loads on the tube bank, on tube plates in which the tubesof the tube bank are lodged, and the housing. Even if thicker tubeplates, tube banks and housing were the answer to these increased loads,in consideration of its manufacture, such a heat exchanger would be oflittle interest.

In practice the load problem is resolved by embodying the apparatus withbellows, which deals with the expansion differences. However, bellowsare fragile and often have a limited mechanical life.

Another solution concerns a construction wherein the tube bank isU-shaped. However, this has the disadvantage that the thermal efficiencyof such an apparatus is less favorable and that internal mechanicalcleaning of the tube bank is difficult or impossible.

A further solution is known wherein the apparatus is embodied with aso-called floating head or moveable end plate. However, this is complex,expensive and susceptible to leakage.

A BRIEF SUMMARY OF THE INVENTION

The object of the invention is to provide a relatively simple,inexpensive and effective apparatus while avoiding the disadvantages ofthe known apparatus.

To this end the apparatus according to the invention is characterized inthat the wall is embodied with tubes incorporated therein or mountedthereon, through which a portion of the medium supplied to the tube bankflows. This pro-vides a very simple and effective construction forachieving that during operation, the wall acquires substantially thetemperature of the tube bank.

An important advantage of the apparatus according to the invention isthat there are no limitations with respect to the allowable temperaturedifference between the primary medium stream and the secondary mediumstream.

The temperature of the wall may be raised to that of the tube bank byoptionally using co-active heating means that are incorporated in ormounted onto this wall.

The apparatus should preferably be constructed such that the tubes ofthe wall have a predetermined diameter and a predetermined mutualdistance, such that during operation the wall acquires substantially thetemperature of the tube bank.

A suitable construction of the apparatus according to the invention ischaracterized in that at their ends, the tubes that are mounted in oronto the wall and the tubes of the tube bank are lodged in tube platesthat connect to, respectively, an inlet pipe connector or outlet pipeconnector for the primary medium stream, and in that the housing at saidends possesses an inlet or outlet, respectively, for the secondarymedium stream. This construction has the additional advantage that itallows the tube length of the tube bank to be used more effectively, dueto which a sought effective heat-exchanging surface can be realized witha tube bank of a shorter length than that of the known apparatus.

The advantage just mentioned can be achieved in particular by embodyingthe apparatus such that the inlet or outlet, respectively, for thesecondary medium stream is embodied as an inlet or outlet conduitsurrounding the tube bank like a housing, and that over approximatelythe width of this inlet or outlet conduit, between adjacent tubes of thewall surrounding the tube bank, gaps are provided for, respectively, theinlet or outlet of the secondary medium stream.

The invention will now be further elucidated by way of an exemplaryembodiment of an apparatus embodied as heat exchanger and with referenceto the drawings, without limiting the claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate one or more embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention. The drawings are only for the purpose ofillustrating one or more preferred embodiments of the invention and arenot to be construed as limiting the invention. In the drawings:

FIG. 1 shows a schematic cross-sectional view of the heat exchangeraccording to the invention, and

FIG. 2 shows a cut-away schematic view of an end of the heat exchangeraccording to the invention.

Identical reference numerals in the figures refer to similar components.

DETAILED DESCRIPTION OF THE INVENTION

With reference first to FIG. 1, reference numeral 1 indicates the heatexchanger according to the invention.

Said heat exchanger 1 has a housing 2, within which housing 2 a tube 3is accommodated. The figures do not show the individual tubes of thetube bank 3. However, to the per-son skilled in the art it is clear howsuch a tube bank 3 is constructed, so that it does not need to be shownin the figure.

The tube bank 3 possesses a first end with a connecting means 4 for theinlet of a primary medium stream 6 and a second end with a connectingmeans 5 for the outlet of said primary medium stream 6. In-and outlet ofa secondary medium stream 7 also takes place via said connecting means 4and 5, usually this occurs in counter-flow with respect to the primarymedium stream 6. The connecting means 5 provided at the second end thusserves for the inlet of the secondary medium stream 7, whereas theconnecting means 4 provided at the first end, serves for the outlet ofthe second medium stream 7.

The housing 2 further possesses a wall 8 extending in the longitudinaldirection of the tube bank 3, which wall according to the invention isequipped such that during operation it acquires substantially thetemperature of the tube bank 3.

To this end the wall 8 is preferably embodied with tubes 9 incorporatedtherein or mounted thereon, through which a portion of the mediumsupplied to the tube bank 3 flows. This is clearly visible in thecut-away view of an end of the heat exchanger 1 as illustrated in FIG.2.

In the construction of the wall 8 shown in FIG. 2 the tubes 9 areincorporated in said wall 8.

Expediently, the tubes 9 of the wall 8 are embodied with a predetermineddiameter and a predetermined mutual distance such that during operation,the wall 8 substantially acquires the temperature of the tube bank 3. Itwill be obvious that the diameter and the distance of the tubes 9 to thewall 8 are in part determined by the diameter of the tubes of the tubebank 3 and the resistance caused by said pipes for the medium flowingthrough said pipes.

FIG. 1, but even more so FIG. 2, shows that the ends of the tubes 9 ofthe wall 8 as well as the tubes of the tube bank 3 are lodged in tubeplates 10, 11. Said tube plates are provided at both sides of the heatexchanger 1, and connect to an inlet pipe connector 12 or an outlet pipeconnector 13, respectively, for the primary medium stream 6.

The FIGS. 1 and 2 further show that at said inlet pipe 12 and outletpipe 13, the housing 2 is provided with an inlet 14 and outlet 15 forthe secondary medium stream 7.

The inlet 14 and outlet 15 for the secondary medium stream 7 areembodied as an inlet conduit or outlet conduit, respectively,surrounding the tube bank 3 like a housing.

Expediently, over approximately the width of said inlet and outletconduit 14,15, between adjacent tubes of the wall 8 surrounding the tubebank 3, gaps 16, 17 are pro-vided for, respectively, the inlet or outletof the secondary medium stream 7. This is clearly shown in FIG. 2. Thesecondary medium stream 7 is thus able to flow around the tubes of thetube bank 3 in the manner known as such, allowing the heat-exchangingcontact via the walls of the tubes of the tube bank 3 with the primarymedium flowing through the tubes to be realized.

As already explained, the invention is not limited to the aboveexemplary embodiment of an apparatus embodied as heat exchanger, but canalso be employed, for example, as reactor for an endothermic chemicalreaction.

To carry out such an endothermic chemical reaction it is possible, forexample, to provide a catalyst in the space surrounding the tubes of thetube bank 3, through which the secondary medium stream 7 can flow. Thissecondary medium stream 7 then needs to contain the reaction mixture forthe formation of the desired chemical product. The reaction heatnecessary for the endothermic reaction may be obtained from the primarymedium stream 6 flowing through the pipes of the tube bank 3. Theconstruction of a chemical reactor embodied in this manner is such as toallow a fast and high conversion ratio for the formation of the desiredchemical product, while it suffices that the reaction mixture stays fora relatively short time in the reactor 1.

It is also possible to provide the catalyst in the tubes of the tubebank 3 and/or the tubes 9 of the wall 8, and to obtain the necessaryreaction heat from the secondary medium 7 flowing around the tube bank3. Thus the primary medium stream 6 carries the mixture of chemicals forforming the desired chemical product.

In an exothermic chemical reaction it may be desirable to be able toremove the developed reaction heat immediately. This may be effected ina manner similar to that used with the apparatus intended forendothermic reactions. If the reaction takes place in the primarystream, the secondary stream serves for the removal of heat and if thereaction takes place in the secondary stream, the primary stream servesfor the removal of heat.

Furthermore, it should be noted that as a rule when the apparatus 1 isembodied as reactor, its dimensioning may well differ greatly from thedimensioning of the apparatus when used as heat exchanger. Moreover, ifthe apparatus is used as chemical reactor, additional measures may benecessary. For example, in order to prevent the catalyst being washedout, it will be necessary to close off the space in which the catalystis introduced by means of a semi-permeable sieve or gauze. However, suchmeasures are completely within the capabilities of the person skilled inthe art and therefore require no further explanation.

1. An apparatus provided with heat-exchanging means comprising ahousing, in which housing a tube bank is accommodated, having at bothsides connecting means for the inlet and outlet of a primary mediumstream and a secondary medium stream, wherein the housing comprises awall that extends in the longitudinal direction of the tube bank, andwherein the wall is embodied with tubes incorporated therein or mountedthereon, through which a portion of the medium supplied to the tube bankflows.
 2. An apparatus according to claim 1, wherein the tubes of thewall have a predetermined diameter and a predetermined mutual distance,such that during operation the wall acquires substantially thetemperature of the tube bank.
 3. An apparatus according to claim 1,wherein at their ends, the tubes that are mounted in or onto the walland the tubes of the tube bank are lodged in tube plates that connect,respectively, to an inlet pipe connector or outlet pipe connector forthe primary medium stream, and wherein the housing at said endspossesses an inlet or outlet, respectively, for the secondary mediumstream.
 4. An apparatus according to claim 3, wherein the inlet oroutlet, respectively, for the secondary medium stream is embodied as aninlet or outlet conduit surrounding the tube bank like a housing, andwherein over approximately the width of this inlet or outlet conduit,between adjacent tubes of the wall surrounding the tube bank, gaps areprovided for, respectively, the inlet or outlet of the secondary mediumstream.
 5. An apparatus according to claim 1, wherein the same isembodied as chemical reactor.
 6. An apparatus according to claim 1,wherein the same is embodied as heat exchanger.